Ambulator control circuitry

Abstract

Control circuitry for producing signals to control motors which propel a mobile platform for a standing paraplegic. Logic circuits connect a 3-axis joy stick controller to four permanent magnet DC motors mounted on the platform such that the platform follows in the direction of the displacement of the joy stick. The joy stick outputs are taken as inputs to several differential amplifiers. Each of a plurality of velocity servo amplifiers receives one input signal from the differential amplifier output and another from a tachometer feedback signal derived from each motor. Comparators receive the velocity servo amplifier outputs as well as a triangular wave input. Each comparator comprises a pulse width modulator which generates pulse outputs whose duty cycle is a function of the voltage inputs to each comparator. The comparator outputs then control motor rotation such that the platform moves in the direction of displacement of the joy stick.

What is claimed is: 
     
       1. A joy stick motor control device comprising: a plurality of electrical motor means for driving a plurality of loads;   a plurality of pulse width modulated signal generators, each having its output connected to one of said plurality of electrical motor means;   a plurality of velocity servo amplifiers, each having its output connected to one of said pulse width modulated signal generators;   a plurality of differential amplifiers each having its output connected to one of said velocity servo amplifiers;   first, second and third joy stick potentiometers operably connected to said plurality of differential amplifiers; and   a three axis joy stick operably coupled to said first, second and third joy stick potentiometers;   wherein said plurality of electric motor means comprises first, second, third and fourth DC motors.   
     
     
       2. The device of claim 1 wherein said plurality of motor means comprises first, second, third and fourth bipolar motor drive channels. 
     
     
       3. The device of claim 1 wherein each said pulse width modulated signal generator comprises a first and second comparator for generating bipolar pulse outputs. 
     
     
       4. The device of claim 3 wherein each said comparator has a triangular wave input. 
     
     
       5. The device of claim 1 wherein each of said plurality of electric motor means comprises an electric motor operable in both forward and reverse directions. 
     
     
       6. The device of claim 5 further comprising: each of said first, second and third joy stick potentiometers having an output   first second and third means connected, respectively, to said first, second, and third potentiometer outputs for providing first, second, and third inverted outputs; and   each of said plurality of differential amplifiers having its input connected to one of said potentiometer outputs and to one said potentiometer inverted outputs.   
     
     
       7. The device of claim 6 wherein said plurality of differential amplifiers comprises first, second, third and fourth differential amplifiers. 
     
     
       8. The device of claim 7 wherein: said plurality of motor means further comprises first, second, third and fourth bipolar motor drive channels, each being connected to one of said plurality of electric motors.   
     
     
       9. The device of claim 8 wherein: each of said plurality of pulse width modulated signal generators comprises first and second comparator means for generating bipolar pulse outputs.   
     
     
       10. An electro-mechanical joy stick motor control device comprising: a three axis joy stick;   means connected to said joy stick for outputting first, second, and third voltages corresponding to the displacement of said joy stick from a rest position;   means responsive to said first, second and third voltages for generating first, second, third and fourth pulse width modulating signals; and   first, second, third and fourth comparators connected to said responsive means for outputting pulse width modulated signals.   
     
     
       11. The device of claim 10 wherein said outputting means comprises: first, second and third joy stick potentiometers.   
     
     
       12. The device of claim 10 wherein said responsive means comprises: first, second, third and fourth differential amplifiers connected respectively to first, second, third and fourth velocity servo amplifiers.   
     
     
       13. The device of claim 12 wherein each of said differential amplifiers has an input that is the sum of two of said first, second and third voltages. 
     
     
       14. The device of claim 10 wherein said first, second, third and fourth comparators each comprises a comparator pair. 
     
     
       15. The device of claim 14 wherein each said comparator pair has a positive and a negative triangular wave input. 
     
     
       16. The device of claim 10 further including first, second, third and fourth motor drive circuits connected, respectively, to said first, second, third and fourth comparators. 
     
     
       17. The device of claim 16 further including first, second, third and fourth DC motors connected, respectively, to said first, second, third and fourth motor drive circuits. 
     
     
       18. A joy stick motor control system for propelling a mobile platform comprising: a three axis joy stick;   first, second and third joy stick potentiometers each being operably coupled to said three axis joy stick and each having an output;   first, second and third means connected to said first, second and third joy stick potentiometers, respectively, for providing first, second and third inverted potentiometer outputs;   first, second, third and fourth means, each being connected to one of said potentiometer outputs and to one of said inverted potentiometer outputs, and each for developing bipolar output signals, and   first, second, third and fourth electric motors each being operable in forward and reverse directions and each being connected to one of said first, second, third and fourth means for developing bipolar output signals.   
     
     
       19. The system of claim 18 wherein: each of said first, second, third and fourth means comprises means for developing pulse width modulated bipolar output signals.   
     
     
       20. The system of claim 19 wherein said first, second, third and fourth means further comprises: first, second, third and fourth pulse width modulated signal generators, each outputting bipolar pulse outputs; and   first, second, third and fourth bipolar motor drive channels, each being connected to one of said first, second, third and fourth pulse width modulated signal generators.